The present invention relates to a molded catalyst for production of triethylenediamine, a method for its production, and a method for producing triethylenediamine employing such a catalyst. More particularly, the present invention relates to an improved crystalline aluminosilicate molded catalyst which is capable of producing triethylenediamine effectively and efficiently from an amine compound.
Triethylenediamine is a useful compound which is used in a large amount as e.g. a foaming catalyst in production of polyurethanes or a curing accelerator for epoxy resins.
Such triethylenediamine can be obtained usually by cyclization of an amine compound by using a catalyst. As such a catalyst, zeolite is well known. For example, {circle around (1)} JP-A-62-228079 and {circle around (2)} JP-A-63-122654 disclose a method of using a crystalline metal silicate subjected to calcination treatment in an air atmosphere at a temperature of from 400 to 600xc2x0 C. and having a molar ratio of silica to alumina of at least 12, as a catalyst; {circle around (3)} JP-A-1-132587 discloses a method of using a pentasyl-type zeolite as a catalyst; {circle around (4)} JP-A-1-143864 discloses a method of using a pentasyl-type zeolite as a catalyst and contacting ethylenediamine, diethylenetriamine or 2-aminoethanol with such a catalyst at a temperature of from 250 to 550xc2x0 C. to obtain triethylenediamiine; {circle around (5)} JP-A-3-133971 discloses a method of employing a pentasyl-type zeolite containing an alkali metal or having aluminum in the zeolite framework isomorphically substituted by iron, as a catalyst, and contacting ethylenediamine with the catalyst at a temperature of from 270 to 420xc2x0 C. to obtain triethylenediamine; {circle around (6)} JP-A-5-17460 discloses a method for producing triethylenediamine from an amine compound and a catalyst composed of a crystalline aluminosilicate subjected to calcination treatment at a temperature of from 500 to 950xc2x0 C. in a steam atmosphere; {circle around (7)} JP-A-5-17461 discloses a method for producing triethylenediamine from an amine compound and a catalyst composed of a crystalline aluminosilicate subjected to calcination treatment at a temperature of from 610 to 950xc2x0 C. in an air atmosphere; {circle around (8)} JP-A-5-17462 discloses a method for producing triethylenediamine from an amine compound and a crystalline aluminosilicate catalyst having an inorganic salt supported thereon; {circle around (9)} JP-A-10-109964 discloses a method for producing triethylenediamine from an amine compound and a zeolite catalyst subjected to basic treatment; {circle around (10)} JP-A-10-182562 discloses a method for producing triethylenediamine from an amine compound and a surface acidity-deactivated zeolite catalyst; and {circle around (11)} JP-A-10-195029 discloses a method for producing triethylenediamine from a triethylenediamine reaction solution having an ethylated compound and a zeolite having a shape selectivity for a condensation reaction and a cyclic reaction added.
As mentioned above, many methods employing zeolite catalysts have been disclosed for the production of triethylenediamine. However, such zeolite catalysts had the following problems when used as industrial catalysts.
In the methods for producing triethylenediamine, the reaction system may be either a batch system, a semibatch system or a continuous system, and the reaction can be carried out in a suspension bed system (a fluidized bed system in the case of a gas phase reaction) or a fixed bed flow system. However, industrially, the fixed bed flow system is advantageous from the viewpoints of operation, apparatus and economical efficiency. In all of Working Examples of the above-mentioned prior art, the reaction is carried out by a fixed bed flow system. In the case of a fixed bed flow system, not only the yield of triethylenediamine, but also the mechanical strength of the molded catalyst and the catalyst life, are very important. With respect to the preparation of the molded catalyst, the prior art gives little specific description of e.g. the molding method, the binder, etc., and has not yet reached a level which is applicable to an industrial fixed bed flow system continuous reactor.
Only {circle around (6)} JP-A-5-17460, {circle around (7)} JP-A-5-17461 and {circle around (8)} JP-A-5-17462 disclose molding methods. These publications mention about extrusion molding, tableting and granulation, but in all Working Examples, tableting is employed.
With respect to the description of a binder, {circle around (2)} JP-A-63-122654 discloses silica, alumina, silica-alumina, etc., {circle around (5)} JP-A-3-133971 discloses alumina oxide, silicon dioxide or a clay such as bentonite or montmorillonite, {circle around (6)} JP-A-5-17460, {circle around (7)} JP-A-5-17461 and {circle around (8)} JP-A-5-17462 disclose silica, alumina, silica-alumina, clay, etc., and {circle around (9)} JP-A-10-109964, {circle around (10)} JP-A-10-182562 and {circle around (11)} JP-A-10-195029 disclose silica, alumina, titania, zirconia and natural clay, but no specific disclosure is made in Working Examples. {circle around (3)} JP-A-1-132587 and {circle around (4)} JP-A-1-143864 mention about an inert binder in Working Examples, but no name of the material is disclosed. Further, {circle around (9)} JP-A-10-109964, {circle around (10)} JP-A-10-182562 and {circle around (11)} JP-A-10-195029 disclose that a material having a low acidity such as silica or zirconia is preferred, since an undesirable side reaction caused by a more active material such as alumina, can be prevented. However, no specific operation or effects are described.
Further, with respect to the yield of triethylenediamine and the catalyst life when triethylenediamine is prepared by means of such a catalyst, for example, by the method disclosed in {circle around (1)} JP-A-62-228079 or {circle around (2)} JP-A-63-122654, the selectivity of triethylenediamine can be increased if the conversion of the starting material is made low, but the selectivity decreases as the conversion increases, and thus, it is not possible to obtain triethylenediamine in good yield, and the decrease in activity of the catalyst with time is significant. By the method disclosed in {circle around (3)} JP-A-1-132587 or {circle around (4)} JP-A-1-143864, the selectivity for triethylenediamine is high, but the conversion of the starting material at that time is low, whereby the yield of triethylenediamine is low, and deterioration with time of the catalytic activity is substantial. By the method of employing an alkali metal ion-containing pentasyl type zeolite as disclosed in {circle around (5)} JP-A-3-133971, the selectivity is high, but the conversion of the starting material is low, and the yield of triethylenediamine is low. On the other hand, with the pentasyl-type zeolite having aluminum in the zeolite framework substituted by iron, the selectivity is high, and as a result, the yield is improved, but the catalyst is a special zeolite, and the method for its production is complex, and the production conditions are severe, the production costs are high, such being not practical from the industrial viewpoint. Although the deterioration with time of the catalytic activity is lower than other conventional catalysts, the improvement is not yet of a level satisfactory from the industrial point of view.
By the method disclosed in {circle around (6)} JP-A-5-17460, {circle around (7)} JP-A-5-17461 or {circle around (8)} JP-A-5-17462, the yield of triethylenediamine is improved, but deterioration with time of the catalytic activity is substantial.
By the method disclosed in {circle around (9)} JP-A-10-109964 or {circle around (10)} JP-A-10-182562, the yield of triethylenediamine is low, and deterioration with time of the catalytic activity is substantial, and such a method is not useful as an industrial production method.
Further, the method disclosed in {circle around (11)} JP-A-10-195029 is a two step reaction, whereby the operation is cumbersome, the installation cost tends to be high, and deterioration of the catalytic activity is also substantial. In the foregoing, various problems of the methods for producing triethylenediamine employing conventional catalysts, have been described, but these problems may be summarized into the following three categories.
(1) The molded catalyst has low strength and is likely to disintegrate into fine powder during the reaction, whereby continuation of the operation becomes impossible. This brings about an increase of the operation pressure especially when the reaction is carried out in a fixed bed flow system, which will be a fatal drawback.
(2) The yield of triethylenediamine in the catalytic reaction is low, such being uneconomical. This brings about not only deterioration of the productivity but also cumbersomeness in the separation and purification of triethylenediamine, and deterioration in the purity of the triethylenediamine product.
(3) Deterioration with time of the catalytic activity is substantial, whereby an industrial stabilized operation tends to be difficult, and the production efficiency tends to be low. This means that the catalyst life is short, thus leading to an increase of the cost for the catalyst and an increase of the work load of replacing the catalyst. Thus, this is a serious problem which must be solved, for the catalytic reaction.
Namely, development of a technique to solve these three problems has been strongly desired for the production of industrially useful triethylenediamine.
The present inventors have conducted an extensive study for a long period of time on the search for a catalyst, on the preparation of the catalyst and on the production of triethylenediamine using the catalyst, in an attempt to find out a technique which is capable of solving the above three problems simultaneously. As a result, they have found a clue for solving the problems by a molded catalyst having a certain specific composition and a specified strength and have finally accomplished the present invention.
Namely, the present invention provides a molded catalyst for production of triethylenediamine, characterized in that (1) the main components are silica and crystalline aluminosilicate, (2) the silica is amorphous, and the content of the silica is from 5 to 70 wt %, (3) the molar ratio of silica to alumina in the crystalline aluminosilicate is at least 12, and the content of the crystalline aluminosilicate is from 30 to 95 wt %, and (4) the hardness is at least 1 kg.
The present invention also provides a method for producing such a molded catalyst for production of triethylenediamine, characterized in that amorphous silica composed of primary particles having an average particle size of from 6 to 60 nm, is used as a binder, and the silica and crystalline aluminosilicate are mixed and then molded into a uniformed shape by a molding machine.
Further, the present invention provides a method for producing triethylenediamine, characterized by contacting at least one member selected from the group consisting of amine compounds having a group represented by the following formula (1):
xe2x80x94CHR1xe2x80x94CHR2xe2x80x94NR3R4xe2x80x83xe2x80x83(1) 
wherein each of R1 to R4 which are independent of one another, is a hydrogen atom or a C1-3 alkyl group which may have a substituent, with such a molded catalyst for production of triethylenediamine.
Now, the present invention will be described in further detail.
Firstly, the molded catalyst for production of triethylenediamine of the present invention will be described.
The catalyst of the present invention comprises silica and crystalline aluminosilicate as the main components. It may further contain a small amount of inorganic compounds and/or organic compounds.
In the present invention, the silica to be used for the catalyst is amorphous and is not crystalline like quartz or cristobalite. This can be easily determined by a powder X-ray diffraction apparatus. When the silica is amorphous, a molded catalyst having a high hardness and a long catalytic life, which are characteristics of the present invention, can be obtained.
In the present invention, the content of silica in the catalyst is from 5 to 70 wt %. If it is less than 5 wt %, a molded catalyst having an industrial hardness may not be obtained, and if it exceeds 70 wt %, the catalytic activity of the molded catalyst tends to decrease. A preferred content is from 15 to 50 wt %. In a case where the main component is not silica but clay or alumina, the hardness of the molded product may be high, but the catalyst life is very short, and such is not included in the present invention.
In the present invention, the active species of the catalyst is crystalline aluminosilicate, and the molar ratio of silica to alumina in this crystalline aluminosilicate is at least 12. If the molar ratio is less than 12, the selectivity for triethylenediamine tends to deteriorate, and an unnecessary byproduct tends to form in a large amount. A preferred molar ratio is from 40 to 5,000, whereby the catalytic activity is high, the selectivity for triethylenediamine is high, and the catalyst life can be prolonged, such being economical. If the molar ratio exceeds 5,000, the catalyst activity tends to decrease, or preparation of such crystalline aluminosilicate tends to be difficult.
In the present invention, the content of the crystalline aluminosilicate in the catalyst is from 30 to 95 wt %. If it is less than 30 wt %, the catalytic activity tends to deteriorate, and if it exceeds 95 wt %, the hardness of the molded catalyst tends to deteriorate. A preferred content is from 50 to 85 wt %, whereby an industrially preferred molded catalyst for triethylenediamine will be obtained.
In the present invention, the crystalline aluminosilicate is preferably one having a main cavity of oxygen ten-membered ring, whereby the catalytic activity and the catalyst life can be increased. Its specific examples include ZSM-5 as disclosed in U.S. Pat. No. 3,702,886, ZSM-8 as disclosed in U.S. Pat. No. 1,334,243, ZSM-11 as disclosed in U.S. Pat. No. 3,709,979, ZSM-12 as disclosed in U.S. Pat. No. 3,832,449, and ZSM-21 as disclosed in U.S. Pat. No. 4,001,346. Among them, ZSM-5 is preferred from the viewpoint of the catalytic activity and the industrial production. Such crystalline aluminosilicate can be obtained usually by hydrothermal synthesis, in which an organic crystallizing agent may or may not be used, and one obtained by any method may be used in the present invention. Further, cations of the crystalline aluminosilicate may not be limited to H-type, and some or all of hydrogen ions may be exchanged with other cations, such as lithium ions, sodium ions, potassium ions, cesium ions, magnesium ions, calcium ions or lanthanum ions. Particularly preferred is crystalline aluminosilicate having ion exchanged with alkali metal ions, particularly sodium ions or potassium ions, from the viewpoint of high yield and suppression of deterioration of the catalytic activity with time.
In the present invention, it is important that the hardness of the catalyst is at least 1 kg. When the hardness is at least 1 kg, it is possible to produce triethylenediamine industrially constantly without disintegration or breakage of the molded catalyst. This is a feature of the catalyst of the present invention and brings about a significant effect when a fixed bed flow system reactor is employed. In the present invention, the hardness means a hardness measured by a crushing strength test method in accordance with xe2x80x9cGranules and agglomerates-Test methods for strengthxe2x80x9d of JIS Z8841 (1993) which is widely used for the measurement of the strength of a molded product. As a testing device for this crushing strength test method, any device corresponding to the testing device as prescribed in xe2x80x9c3.1.1. Testing devicexe2x80x9d of JIS Z8841 may be employed without any particular restriction. As such a testing device, a Kiya model hardness meter is, for example, preferred. A manual type and an automatic type are available for the Kiya model hardness meter, and either one can be used with good precision. The press chip here is a standard of 5 mm in diameter, which is suitable for measuring molded products of various shapes. The hardness in the present invention represents a value measured by this Kiya model hardness meter with a press chip of 5 mm in diameter. This hardness is preferably from 2 to 20 kg, whereby the molded catalyst can be used constantly for a long period of time even under severe conditions. If the hardness is too high, not only a special apparatus will be required for molding, but also the activity of the molded catalyst tends to be low to some extent, probably because the pore volume of the molded catalyst decreases. More preferably, the hardness is from 3 to 15 kg.
In the present invention, the shape of the molded catalyst is not particularly limited. However, from the viewpoint of production efficiency, handling efficiency, stability of the shape of the molded product during the preparation of triethylenediamine and maintenance of the catalytic activity, it is preferably spherical, oval or cylindrical, and its average diameter as a sphere is preferably from 1 to 20 mm. If the shape is irregular and has many angular corners, breakage is likely to take place during handling or during operation, thus leading to an increase of the operation pressure due to the formed powder. The average diameter as a sphere is an average diameter obtained by calculating the volume from the geometrical shape of the molded product as a sphere. Here, some examples of the relation between the size of a cylindrical molded product and the average diameter as a sphere, are shown in Table 1.
In the present invention, this average diameter as a sphere is more preferably from 2 to 10 mm, whereby the above-mentioned effects can be obtained at a higher level. If the average diameter as a sphere is small, the hardness decreases, or the pressure loss of the catalyst layer increases. On the other hand, if the average diameter as a sphere is large, the hardness will be high, but the apparent specific area decreases, whereby the catalytic performance decreases. Further, drift of the product and starting material for the production of triethylenediamine will take place, whereby the reaction efficiency decreases.
Now, a method for producing the molded catalyst for production of triethylenediamine of the present invention will be described.
For the production of the catalyst of the present invention, firstly amorphous silica composed of primary particles having an average particle size of from 6 to 60 nm, is used as a binder, and such silica and crystalline aluminosilicate are mixed. It is possible to obtain a molded catalyst having a good shape and high hardness, when such amorphous silica composed of primary particles of from 6 to 60 nm, is used as the binder. If the primary particle size of such silica is smaller than 6 nm, the mixing and molding operation tends to be difficult, and it will be difficult to increase the hardness of the molded product. Further, the catalytic activity of the molded product tends to be low, and the catalyst life tends to be short. The reason may be such that since the primary particle size of the silica is small, the pore size of the molded catalyst will be small, whereby the reactivity decreases. On the other hand, if the primary particle size is larger than 60 nm, the mixing and molding operation may be easy, but the hardness of the molded product tends to be small, and disintegration or breakage tends to occur during use of the molded product. Such a primary particle size can easily be measured and identified by SEM (scanning electron microscope) or TEM (transmission electron microscope). Further, the average size of the primary particles can also be obtained from the measurement of the specific surface area by e.g. a BET apparatus, because the primary particles of silica such as colloidal silica, wet process silica and dry process silica are spherical in most cases, and even if their average particle size is obtained from the specific surface area and the true density as spheres, an error is small. This relation may be represented by the following formula:   D  =            6              2.2        ⁢        S              xc3x97          10      3      
where
D: Average primary particle size (nm) of silica
S: Specific surface area (m2/g) of silica
2.2: True density (g/cm3) of silica, which may vary depending on hydrous or anhydrous, but here 2.2 g/cm3 was employed.
6: Shape factor (xe2x88x92) of spheres
From this formula, the specific surface area of silica having an average primary particle size of from 6 to 60 nm is calculated to be from 50 to 500 m2/g. This is effective for selection of silica to be used.
In the method of the present invention, this silica binder is amorphous and consists essentially of silica, and its silica content is preferably at least 90%. It may contain, as trace constituents, oxides of alkali metals, alkaline earth metals or transition metals. More preferably, the silica content is at least 95 wt %.
In the method of the present invention, as such a silica binder, at least one member selected from the group consisting of colloidal silica, wet process silica and dry process silica, is preferred. Each of them is amorphous. Colloidal silica can be produced by e.g. an ion exchange method, and it is one having spherical primary particles mono-dispersed in an aqueous solution. As commercial products, LUDOX, SYTON, NALCOAG, SNOWTEX, etc., are available. The silica concentration in such colloidal silica is usually from 10 to 50 wt %. Wet process silica is produced by treating an aqueous sodium silica solution with a mineral acid such as sulfuric acid to precipitate silica, and it is called also as white carbon. This is a hydrous silicic acid, and as commercial products, Hi-Sil, Ultrasil, Vulcasil, Santocel, ValronEstersil, Tokusil, Nipsil, etc., are available. Dry process silica is produced by hydrolyzing mainly silicon tetrachloride gas at a high temperature in an oxygen atmosphere, and it is called also as fumed silica. This is anhydrous silicic acid, and as commercial products, Aerosil, Reolosil, Cab-O-Sil, Fransil, DC. Silica, ArcSilica, etc., are available. Among these silicas, colloidal silica is preferred, whereby mixing and molding operation are easy, and a molded product having higher hardness can be obtained. Further, its catalytic performance is high, and the catalyst life can be particularly prolonged.
In the method of the present invention, mixing of the silica and crystalline aluminosilica is not particularly limited so long as they can be uniformly mixed. The apparatus may, for example, be a rotating container type mixer of e.g. cylindrical form, V form, cubic form, double circular cone form, hexagonal form or pyramid form, a fixed container type mixer such as a screw mixer, a ribbon mixer, a Henschel mixer or a rotation pan mixer, or a mixing/kneading machine such as a plast mill. In this mixing operation, it is preferred to use water, whereby mixing can be made more uniformly, and the mixture will have tenacity, whereby the subsequent molding will be facilitated. Further, at the time of mixing, an organic binder such as gum arabic, sodium alginate, processed starch, sodium casein, sodium carboxymethyl cellulose, glycerol, gelatin, starch, molasses, fine crystalline cellulose, pitch, hydroxypropyl cellulose, phenol resin, sodium polyacrylate, polyethylene glycol, polyvinyl alcohol, polyvinyl pyrrolidone, methyl cellulose or lignin, may be added, so that the subsequent molding operation will be improved.
In the method of the present invention, the mixture thus obtained, will then be molded. For the molding, a dry method and a wet method are available, and either method may be used for the present invention. Specifically, the molding method may, for example, be extrusion molding, tableting, tumbling granulation, agitation granulation or roll pressing, and any one of them may be used in the present invention. The shape of the molded product to be obtained by such molding will be spherical, oval, cylindrical or tablet-form, and any one of them may be used in the present invention. With respect to the size, the average diameter as a sphere is preferably from 1 to 20 mm, more preferably from 2 to 10 mm. In the case of dry molding, it is preferred to calcine the molded product, whereby the hardness of the molded product will be improved. In the case of wet molding, it is preferred to dry the molded product, followed by calcination, whereby the hardness of the molded product will be further improved.
In the method of the present invention, a preferred embodiment of mixing and molding is such that wet mixing employing water, is followed by extrusion molding and then by drying and calcination, whereby it is possible to obtain a molded catalyst for production of triethylenediamine, having high hardness and good catalytic performance. A molded product obtained by wet molding is usually dried. The drying temperature is usually from 40 to 200xc2x0 C., and the drying time is usually from 1 to 24 hours. The atmosphere at that time may be nitrogen, air or the like. In a preferred embodiment, calcination is carried out after molding or drying.
In the method of the present invention, calcination may be carried out in an air atmosphere or in a steam atmosphere. The calcination conditions vary depending upon the type of crystalline aluminosilica, the molar ratio of silica to alumina thereof, the type of an organic crystallizing agent employed, the type of the binder for molding, etc. However, in any case, the temperature is preferably from 500 to 950xc2x0 C. A more preferred temperature is from 550 to 850xc2x0 C. The calcination time is usually at least 1 hour, preferably at least 3 hours. If the calcination temperature is low, for example, at a level of lower than 500xc2x0 C., the hardness of the molded catalyst tends to be slightly low. Further, the selectivity for triethylenediamine as the desired product, tends to be slightly low. On the other hand, if the calcination temperature is high, for example, at a level of higher than 950xc2x0 C., the crystallizability of the crystalline aluminosilicate deteriorates due to the heat, and the specific surface area tends to be small, whereby the activity as a catalyst deteriorates. At a temperature of from 550 to 850xc2x0 C., it is possible to obtain a molded catalyst for production of triethylenediamine, which is excellent in the catalytic activity, the catalyst life and the hardness.
In the method of the present invention, after calcination of the molded product, post treatment such as ion exchange may be carried out. The ion exchange operation may be carried out at any stage during the production of the molded catalyst. However, it is preferably carried out after calcination, whereby the operation is easy, and the performance of the molded catalyst can further be increased. Cations of crystalline aluminosilicate after the ion exchange may be at least one type selected from the group consisting of hydrogen ions, lithium ions, sodium ions, potassium ions, cesium ions, magnesium ions, calcium ions and lanthanum ions. Among them, alkali metal ions, particularly sodium ions or potassium ions, are preferred, whereby a high yield and high catalytic activity with time, can be obtained for the production of triethylenediamine.
Now, a method for producing triethylenediamine employing the molded catalyst of the present invention, will be described.
The compound used as a starting material in the method of the present invention is an amine compound having a group represented by the following formula (1):
xe2x80x94CHR1xe2x80x94CHR2xe2x80x94NR3R4xe2x80x83xe2x80x83(1) 
wherein each of R1 to R4 which are independent of one another, is a hydrogen atom or a C1-3 alkyl group which may have a substituent. The compound may, for example, be monoethanolamine, diethanolamine, isopropanolamine, diisopropanolamine, N-(2-aminoethyl)ethanolamine, N-(2-hydroxyethyl)piperazine, N,Nxe2x80x2-bis(2-hydroxyethyl)piperazine, N-(2-aminoethyl)piperazine, N,Nxe2x80x2-bis(2-aminoethyl)piperazine, piperazine, ethylenediamine, diethylenetriamine, triethylenetetramine or tetraethylenepentamine, and any of these may be used. Among these, a chain ethyleneamine such as ethylenediamine, diethylenetriamine, triethylenetetramine or tetraethylenepentamine, or a cyclic ethyleneamine such as N-(2-aminoethyl)piperazine or piperazine is preferred, since not only it is available in a large amount at a low cost, but also triethylenediamine and piperazine can be produced in higher yields. The more preferred ethyleneamine is N-(2-aminoethyl)piperazine. Such amine compounds may be used alone or in combination as a mixture of two or more of them.
In the method of the present invention, the reaction is carried out in a fixed bed flow system, and it may be carried out either in a gas phase or in a liquid phase.
It is advantageous to carry out the reaction by a gas phase system from the viewpoint of operation, yield and stability of the catalyst. In such a case, as the diluent for the amine compound, a gas such as nitrogen gas, hydrogen gas, ammonia gas, water vapor or a hydrocarbon, may be employed. Otherwise, a solvent such as water or a hydrocarbon, may be employed to dilute the amine compound, and the diluted amine compound may be introduced as the starting material and gasified in the reactor. Such a diluent may be used in an optional amount, and usually the molar ratio of the amine compound to the diluent is preferably from 0.01 to 1. If the molar ratio is smaller than 0.01, productivity of triethylenediamine tends to be low. On the other hand, if the molar ratio is larger than 1, the selectivity for triethylenediamine will slightly decrease.
In the present invention, an amine compound is used as the starting material and contacted with the above molded catalyst to produce triethylenediamines. The reaction conditions such as the reaction temperature and the space velocity at that time, vary depending upon e.g. the types of the crystalline aluminosilicate and the amine compound, and can not absolutely be determined. Usually the reaction is suitably carried out at a reaction temperature of from 250 to 450xc2x0 C. at a space velocity (GHSV) of from 100 to 10,000 hrxe2x88x921. Further, the reaction may be carried out under either atmospheric pressure, elevated pressure or reduced pressure.
By this catalyst reaction, triethylenediamine can be obtained effectively and efficiently. At that time, piperazine is also obtained as a byproduct. Piperazine is also a useful compound like triethylenediamine, and is useful also as a starting material for production of triethylenediamine.
Further, the molded catalyst of the present invention has high hardness and a long catalyst life, as compared with conventional catalysts. Accordingly, it undergoes gradual deterioration of the catalytic activity by the reaction for a very long period of time. However, by removing organic components attached to the catalyst by calcination, it can be reproduced as a highly active catalyst and can be repeatedly used. This indicates that the catalyst is not essentially changed, and this is an important feature of the present invention. For the activation of the used catalyst, a calcination temperature of at least 500xc2x0 C. is usually preferred.
Now, the present invention will be described in further detail with reference to Examples. However, it should be understood that the present invention is by no means restricted to such specific Examples.